1. Field of the Invention
The invention relates to a vacuum cleaner with a cyclonic dirt separator having a first cyclone and a plurality of downstream secondary cyclones. In one of its aspects, the invention relates to a cyclonic dirt separator with secondary cyclones arranged around the first cyclone to provide an unobstructed view of at least a portion of the first cyclone. In another of its aspects, the invention relates to a cyclonic dirt separator with a dirt cup assembly mounted below the cyclones and a working air conduit that extends through the first cyclone and the dirt cup assembly. In another of its aspects, the invention relates to a cyclonic dirt separator with secondary cyclones having a vortex stabilizer.
2. Description of the Related Art
Cyclone separators are well-known. Some follow the textbook examples using frustoconical shape separators, and others use high-speed rotational motion of the air/dirt to separate the dirt by centrifugal force. Typically, working air enters and exits at an upper portion of the cyclone separator, and the bottom portion of the cyclone separator is used to collect debris. Furthermore, in an effort to efficiently distribute weight of and upright vacuum cleaner, the suction source that creates the working air flow is typically placed at the bottom of a handle assembly and below the cyclone separator. This arrangement, therefore, requires an exhaust air path from an upper portion of the cyclone assembly and down the handle to the suction source. This airpath can be tortuous and formed by multiple parts that can allow for air leaks, which negatively impact airflow and, necessarily, cleaning performance.
U.S. Pat. No. 6,238,451 to Conrad discloses a cyclonic separator in a vacuum cleaner comprising a single first stage cyclone and a plurality of vertically aligned secondary downstream cyclones arranged in parallel relative to one another. The secondary cyclones are located within the same perimeter of and directly above the upstream cyclone. This arrangement of cyclones necessarily creates a tall unit because the downstream cyclones are located above the upstream cyclone.
U.S. Pat. No. 6,607,572 to Dyson discloses a cyclonic separating apparatus with upstream and downstream cyclonic units, wherein the downstream units comprise a plurality of downstream cyclones located above the upstream cyclone and inverted relative to the upstream cyclone.
U.S. Pat. No. 6,070,291 to Bair et al. and its progeny shortens the air path from the cyclone exhaust to the motor inlet. These patents disclose a pleated cylindrical filter in a cyclonic chamber whereby the working air is drawn through the cylindrical filter, through the bottom of the cyclonic chamber, through another filter, and directly into the suction source inlet. The suction source is in a vertical position below the cyclonic chamber. The vertical orientation of the suction source is undesirable due to the amount of space needed at the bottom of the handle to accommodate the suction source in this position. Additionally, the motor shaft of the vertically oriented suction source cannot be utilized to power a horizontal axis agitator.
U.S. Pat. No. 6,341,404 to Salo et al. discloses a bottom discharge cyclone chamber with the suction source mounted horizontally below the cyclone chamber. However, motor exhaust air is redirected back up into an annular exhaust plenum located below the cyclone chamber, and the motor exhaust exits from the exhaust plenum in a radial fashion. This exhaust path includes a number of turns, which tend to create backpressure and, therefore, reduce efficiency.
U.S. Pat. No. 6,129,775 to Conrad discloses a cyclone separator with a number of different forms of flow inhibitors, such as a terminal insert, to interfere with airflow within the cyclone separator. As shown in FIG. 14(d), the terminal insert can comprise a plurality of longitudinally extending members, such as rods, which extend upwardly into the cyclone separator cavity from the bottom surface of the cyclone separator. The rods are said to interact with circulating fluid to disrupt its rotational motion. The rods can be positioned symmetrically or non-symmetrically around longitudinal axis of the separator. The rods can be a variety of shapes such as, in transverse section, squares, ellipses or other closed convex or abode shapes. Further, the transverse section of rods can vary longitudinally.
U.S. Patent Application Publication No. 2005/00500678 to Oh et al. and its progeny disclose a cyclone dust separating apparatus comprising a primary cyclone and a plurality of downstream secondary cyclones arranged around the primary cyclone. As a result of this configuration, the secondary cyclones obstruct the view of the primary cyclone, and the user cannot visually observe the operation of the primary cyclone. Additionally, the working air exiting the secondary cyclones exits the cyclone dust separating apparatus through an upper opening.